Question: I was wondering back in November we had a sewer problem we have
taken care of that but since then we have a quite a problem with little
flies that look like fruit flies. I was told that they were sewer flies
and we have tried everything to get rid of them. THey will go away for a
couple of weeks and then come back like twice as many is this something
that you could help me with.
ANSWER I think you may have what are called phorid flies, they are also known (in some areas) as sewer flies. This may be a good name for them, since they are often associated with damage to sewer lines that are in or close to the house or building. However, these flies are just as often found near clogged drains inside buildings.
These are small brown to blackish brown flies that have a 'jerky' or erratic walking behavior. The adults will sometimes collect at windows, but often remain close to the breeding site. They do not bite .
The immature stages of these flies live in the organic matter in drains. They are sometimes found in the soil around drain pipes or sewer lines that have broken. The presence of phorid flies is an indication that high level organic material is present.
These flies are difficult to control with any chemicals. The situation has to be assessed and the source of the infestation pinpointed. Is it a clogged drain or a broken pipe, is it a clogged sewer line or a broken sewer line? Spraying insecticide into the pipe to kill the adult flies will rarely solve the problem. When the breeding site is corrected, the adult flies will disappear.
